1. Field of the Invention
The present invention relates to broadband light source devices.
2. Description of the Related Art
Supercontinuum light (SC light) is a type of broadband light that has a high-output, broad-band, and flat spectrum. For this reason, SC light is expected to be used in various fields of application, such as for light measurement and near-infrared spectroscopy. In particular, SC light in a visible range of 400 nm to 700 nm is much researched for its application to displays.
Page 14 of the document “FemtoFiber Lasers” in TOPTICA Photonics AG's Internet website (URL: http://wwwtoptica.com/products/itemla_yer/97/BR-41003E-FFS-2006-12.pdf, searched on Apr. 11, 2007) describes a broadband light source device FFS.SYS-SHG-PCF. In this broadband light source device, an erbium-doped fiber laser is used as a seed light source, and an output laser beam is guided to a photonic crystal fiber (PCF) where a nonlinear optical phenomenon is caused to occur. Utilizing this nonlinear optical phenomenon, SC light in a visible range is generated. However, in a seed light source including an erbium-doped fiber laser, a light amplifier such as an erbium-doped fiber amplifier is used in order to obtain high output necessary for wavelength conversion. This unfavorably leads to problems such as an increase in cost and a distorted waveform of the output light. A distorted waveform of the output laser beam (i.e. an incident beam on a PCF) leads to a lower wavelength conversion efficiency, thus making it difficult to obtain high-intensity and stable SC light.